Dies for crimping electrical connectors



May

N, C. GRAEFF DIES FOR CRIMPING ELECTRICAL CONNECTORS Filed Feb. 25} 1960 2 heetsSheet 1 Ills??? r 3a A m g 2.0

INVENTOR. Nora/00d C Graeff BY M W 2 I May 14, 1963 N C. GRAEFF DIES FOR CRIMPING ELECTRICAL CONNECTORS Filed Feb. 25, 1960 2 Sheets-Sheet 2 INVENTOR.

O Bil Vorwood C raeff United States Patent M 3,959,532. DIES FUR CRIMPING ELECTRICAL CGNNECTURS Norwoed Q. Graefi, Port Trevor-ton, Pan, assignor to AMP Incorporated, Harrisburg, Pa. Filed Feb. 23, 196i), er. No. 1933i) 1 Claim. ((11. 153 1 In cold-Welding electrical ferrule-type connectors onto conductors, it is customary to insert the conductor into the ferrule and deform the connector onto the conductor by means of a pair of dies. It has been discovered that prior known types of crimping dies have had serious disadvantages, particularly when used on large-sized conductors, -i.e., 4/0 and larger. It has been observed that it has been particularly difiieult to crimp terminals of this size because of the difficulty in the uniform reduction of wires, breakthrough of the tin plate, formation of metal flash, and deformation of the indenter. It is an object of this invention to provide a crimping die for electrical connectors which will eliminate these undesirable characteristics. It is also an object of this invention to provide a crimping die which has a rounded crimping nest and a crimping indenter which is round in the middle and flat on the outer edges.

Other objects and attainments of the present invention will become apparent to those skilled. in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there is shown and described an illustrative embodiment of the invention; it is to be understood, however, that this embodiment is not intended to be exhaustive nor limiting of the invention but is given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIGURE 1 is a perspective view of a set of dies embodying the principles of this invention;

FIGURE 2 is a front plan view of the dies shown in FIGURE 1 with a ferrule-type connector inserted therebetween;

FIGURE 3 is a sectional view taken through plane 33 of FIGURE 4, illustrating the dies and connectors of FIGURE 2 in crimped relationship;

FIGURE 4 is a top plan view showing an electrical connector crimped onto a conductor with the die members shown in phantom;

FIGURE 5 is a view similar to FIGURE 4 showing a different embodiment; and

FIGURE 6 is a side view of FIGURE 5.

As shown in the drawings, the die set is comprised of a lower die It and an upper die 12 (FIGURE 1). The bottom die may be considered a nest and has an arcuate working surface 14 which has a radius larger than the ferrule member 16. The working surface has a pair of opposed side surfaces 18 and 20. A die holding member 22 is secured to the die to mount the die in a crimping tool.

The upper die may be termed an indenter. The die surface has an inner radial surface 24 which is equal to the working surface 14. A pair of lands 26 and 28 project outwardly from the arcuate surface 24. The width of the indenting die is slightly less than the distance between the opposed working surfaces 18 and 2% of the nest. Thus the indenting die fits snugly into the nest (FIGURE 3). Another pair of lands 3d and 32 extends from the sides of the indenting die, and in the assassa Fatented May 14, 1963 closed position abut the top of the nest to prevent overcrimping.

When it is desired to crimp a ferrule and conductor in the dies, the conductor is inserted into the ferrule and the ferrule placed between the dies. The dies are brought together until the lands 3i) and 32 abut the top of the working surfaces 18 and 20 (FIGURE 3). As shown in FIGURE 3, the fiat land surfaces and 28 cause deformation of the outer strands of the conductor within the ferrule. The round working surface 24 causes the same deformation of wire strands in the central portion of the conductor. The over-all effect is to provide a crimped section 4 having a uniform deformation of wire strands throughout the crimped cross-section. Also, the smooth, gentle design of the indenting die from the flat land portions 26 and 23 through the larger arcuate working surface 24 prevents the crimping pressure from springing the U-shaped indenting die and causing it to fracture after repeated crimping. Additionally, the tin plate on the outside of the erimpe-d ferruie is not punctured or disturbed. The configuration of the crimped section does not provide any flashed surfaces of metal which would be harmful in an electrical connection.

The form or embodiment of the invention shown in FIGURES 5 and 6 is similar to that shown in FIGURES 1 and 4. Instead of a single, smooth die surface, a pair of axially disposed die surfaces is provided which effect spaced, crimped sections 42, 44. Alternatively the crimp may be made in two stages, making each crimp separately. Thus the metal at each end of the crimped connection is extruded, causing a considerable increase in the tensile strength of the connection.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claim when viewed in its proper perspective against the prior art.

I claim:

A die set for crimping ferrule-type connectors onto conductors including: a first nesting die having a concave arcuate bottom working surface and oppose-d side surfaces tangent to the extremities and forming a continuation of said arcuate working surface, a second indenting die having opposed side surfaces narrower than the opposed side surfaces of the nesting die, an intermediate concave arcuate working surface between the opposed side surfaces of the indenting die, and a pair of parallel lands on the indenting die adapted to relieve stress concentration on the indenting die and distribute the crimping force more evenly through the connector, said lands being coplanar and disposed so that one land is on each side of the arcuate working surface and extends from an edge of the arcuate working surface to one of the opposed side surfaces, whereby the connector may be crimped onto the conductor Without the formation of sharp side edges.

References Cited in the file of this patent UNITED STATES PATENTS 2,242,280 Adams et al. May 26, 1941 2,426,492 Dupre Aug. 26, 1947 2,534,867 Hennessey Dec. 19, 1950 2,732,615 Sandberg Jan. 31, 1956 2,802,257 Holtzapple Aug. 13, 1957 2,837,135 Demler June 3, 1958 2,965,147 Hoffman Dec. 20, 1960 

